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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_regex.background.thread_safety"></a><a class="link" href="thread_safety.html" title="Thread Safety">Thread Safety</a>
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<p>
        The Boost.Regex library is thread safe when Boost is: you can verify that
        Boost is in thread safe mode by checking to see if <code class="computeroutput"><span class="identifier">BOOST_HAS_THREADS</span></code>
        is defined: this macro is set automatically by the config system when threading
        support is turned on in your compiler.
      </p>
<p>
        Class <a class="link" href="../ref/basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a>
        and its typedefs regex and wregex are thread safe, in that compiled regular
        expressions can safely be shared between threads. The matching algorithms
        <a class="link" href="../ref/regex_match.html" title="regex_match"><code class="computeroutput"><span class="identifier">regex_match</span></code></a>,
        <a class="link" href="../ref/regex_search.html" title="regex_search"><code class="computeroutput"><span class="identifier">regex_search</span></code></a>,
        and <a class="link" href="../ref/regex_replace.html" title="regex_replace"><code class="computeroutput"><span class="identifier">regex_replace</span></code></a>
        are all re-entrant and thread safe. Class <a class="link" href="../ref/match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a> is now thread safe,
        in that the results of a match can be safely copied from one thread to another
        (for example one thread may find matches and push <a class="link" href="../ref/match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a> instances onto a queue,
        while another thread pops them off the other end), otherwise use a separate
        instance of <a class="link" href="../ref/match_results.html" title="match_results"><code class="computeroutput"><span class="identifier">match_results</span></code></a>
        per thread.
      </p>
<p>
        The <a class="link" href="../ref/posix.html" title="POSIX Compatible C API's">POSIX API functions</a> are
        all re-entrant and thread safe, regular expressions compiled with regcomp
        can also be shared between threads.
      </p>
<p>
        The <a class="link" href="../ref/deprecated/old_regex.html" title="High Level Class RegEx (Deprecated)">class RegEx</a>
        is only thread safe if each thread gets its own RegEx instance (apartment
        threading) - this is a consequence of RegEx handling both compiling and matching
        regular expressions.
      </p>
<p>
        Finally note that changing the global locale invalidates all compiled regular
        expressions, therefore calling <code class="computeroutput"><span class="identifier">set_locale</span></code>
        from one thread while another uses regular expressions will produce unpredictable
        results.
      </p>
<p>
        There is also a requirement that there is only one thread executing prior
        to the start of main().
      </p>
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<td align="right"><div class="copyright-footer">Copyright © 1998-2013 John Maddock<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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